Question: Is ${721888}$ divisible by $4$ ?
Answer: A number is divisible by $4$ if the last two digits are divisible by $4$ . [ Why? We can rewrite the number as a multiple of $100$ plus the last two digits: $ \gray{7218} {88} = \gray{7218} \gray{00} + {88} $ Because $721800$ is a multiple of $100$ , it is also a multiple of $4$ So as long as the value of the last two digits, ${88}$ , is divisible by $4$ , the original number must also be divisible by $4$ Is the value of the last two digits, $88$ , divisible by $4$ Yes, ${88 \div 4 = 22}$, so $721888$ must also be divisible by $4$.